ITTO20130565A1 - SYSTEM FOR ACTIVE CONDITIONING OF A GASEOUS SUCTION FLUID OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

DESCRIPTION OF THE INDUSTRIAL INVENTION ENTITLED: "System for the active conditioning of a gaseous suction fluid of an internal combustion engine"

DESCRIPTION

The present invention relates in general to systems for conditioning the gaseous fluids (air or air-recirculating exhaust gas mixtures) entering internal combustion engines.

It is known that in the design of systems for feeding air or air-gas mixtures in internal combustion engines, problems of different kinds are faced, which require conditioning of the fluids entering the engine.

In particular, the increasingly restrictive regulations on emissions require a continuous technological effort to improve performance; every parameter that affects fuel consumption and emission levels is therefore the subject of a study aimed at this improvement. In this regard, the development of a system that guarantees an optimal temperature trend of the intake air in all driving conditions (from engine warm-up to the condition of "wide open throttle" - WOT) can become an important tool for compliance with future engine emission regulations.

In addition, the common down-sizing trend among automotive manufacturers requires the development of solutions with high specific power, in particular through the use of a turbocharger that compresses the intake air.

In the past, various systems for controlling the intake air temperature have been developed and applied to mass production.

For example, some manufacturers have developed a bypass system for an air-powered intake air cooler, used to reduce CO / HC emissions during the engine warm-up phase.

Another manufacturer has instead proposed a flow rate modulation technique, generated by an auxiliary electric pump, of the water that feeds an intake air cooler in order to maintain a constant temperature of the intake gases at the engine inlet. The aforementioned pump is kept inactive during the engine warm-up phase, until a target temperature is reached.

This technology was further developed as described in US 2011/0088664. This publication describes a suction system comprising a water-fed suction air cooler, and an additional bypass branch, which are controlled by a double valve. The aforementioned arrangement allows to selectively cool, partially cool or not cool the charge air inlet to the engine depending on the speed of the same.

In particular, the present invention relates to an intake system for a supercharged internal combustion engine of a motor vehicle, comprising

an intake duct having a first end connectable to a supercharging compressor, and a second end connectable to a plurality of engine cylinders for supplying a gaseous intake fluid to said cylinders, in which said intake ducting includes a line cooling comprising:

a high temperature cooler and a low temperature cooler arranged in series along said intake duct, and fed with a cooling fluid designed to cool the gaseous intake fluid, said cooling fluid being fed by a power supply system on board the motor vehicle; and a by-pass branch arranged in parallel with said low temperature cooler, said bypass branch and said low temperature cooler being selectively connected at the outlet to said high temperature cooler.

A system of this type is described in the article "Turbocharging with low temperature charge air cooling and EGR" by Carsten Guhr and Hans Zellbeck (MTZ 10/2012, vol. 73, pp. 44-52). This system has been proposed to improve the dynamic behavior of petrol engines, in particular under low speed load conditions. An increase in the efficiency of the engine is also identified in stationary conditions and close to the maximum operating torque curve.

An object of the present invention is to propose a system capable of following in a relatively more precise way an optimal desired temperature curve of the gaseous suction fluid in any running condition.

This object is achieved according to the invention by a suction system of the type defined above, further comprising a heating line with a heater provided to heat the gaseous suction fluid, said heating line being arranged in parallel with said cooling line, in which said suction system is configured modulable between a heating mode in which the gaseous suction fluid is heated through said heater, and a cooling mode in which the gaseous suction fluid is cooled through at least one of said high temperature cooler and low temperature cooler.

As can be appreciated, such a system has a high number of degrees of freedom, due to the fact that it is based on different adjustment parameters (flow rates of suction fluid respectively distributed to the heater and coolers, electrical power fed to the heater, fluid flow rates of cooling fed to the coolers); in this way, the adjustment can take place in such a way as to approximate as precisely as possible an ideal temperature curve.

Preferred embodiments of the invention are defined in the dependent claims, which are to be understood as an integral part of this description.

Further features and advantages of the suction system according to the invention will become clearer with the following detailed description of an embodiment of the invention, made with reference to the attached drawings, provided for illustrative and non-limiting purposes only, in which:

Figure 1 is a diagram representing an aspiration system according to the present invention;

Figure 2 is a diagram representing a conditioning module for the suction system of Figure 1;

- Figure 3 is a graph that compares a temperature curve of the intake air in a system with a conventional cooler and an optimal temperature curve, as the driving conditions of a vehicle vary; And

- Figures 4 to 6 represent the conditioning module of Figure 2 in different operating modes, associated with the respective running conditions of the vehicle.

Figure 1 shows a conventional internal combustion engine 20 comprising a plurality of cylinders 21, and an intake duct 30 whose first end 31 is connected at the outlet to a supercharging compressor C, and a second end 32 of which is connected at the inlet to the cylinders 21 of the engine for feeding a gaseous intake fluid. This gaseous fluid can be air or an air / recirculating exhaust gas mixture, in the case of engines that exploit the recirculation of the engine exhaust gases.

The engine 10 can be a supercharged engine with compression ignition (for example a diesel engine) or a supercharged engine with positive ignition (for example a petrol engine).

The suction duct 30 also comprises a conditioning module 33 object of the present invention, for conditioning the gaseous suction fluid, which will be described in detail below. Figure 1 also shows a conventional external air supply duct 34, connected at the inlet to the compressor C to feed external air to the intake duct 30, and along which an air filter 35 and a diverter valve 36 are arranged. To the diverter valve 36 there is also conventionally connected at the inlet a recirculation duct 37a (optional) for the recirculation of the exhaust gases. Figure 1 also shows a turbine T set in rotation by the engine exhaust gases and integral in rotation with the compressor C, an after-treatment component 38 for the treatment of the exhaust gases, and a diverter valve 39, to selectively route the exhaust gases to the recirculation pipe 37 or to an exhaust system. Figure 1 also shows a high pressure recirculation duct 37b conventionally provided for the recirculation of the high pressure exhaust gases, which may or may not be present, depending on the application circumstances.

With reference also to Figure 2, the conditioning module 33 comprises a high temperature cooler 331, a low temperature cooler 332 and a heater 333. By "module" it is meant that the above components can be integrated / assembled inside a a support and interconnection structure, so as to form a single constructive unit.

The high temperature cooler 331 is fed with a cooling fluid, in particular water (mixture of water and ethylene glycol or other refrigerant substance), and is connected to a cooling fluid supply circuit, comprising a pump P1.

The low temperature cooler 332 is fed with a cooling fluid, in particular water (a mixture of water and ethylene glycol or other refrigerant substance), and is connected to a second cooling fluid supply circuit, comprising a pump P2. The conditioning of the cooling fluid circulating in the aforementioned low temperature supply circuit is carried out according to known technical systems; the low temperature circuit is used to directly feed the low temperature cooler and, alternatively or in combination, a storage tank for the low temperature fluid possibly present in the circuit, and provided to feed the low temperature cooler during the rapid motor transient. In an alternative embodiment, a single power supply circuit may be provided which supplies both coolers 331 and 332.

The heater 333 is an electrical heater, for example a heater with a heating resistor having positive temperature coefficient (PTC) behavior.

Inside the cooling duct 30 the high temperature cooler 331 and the low temperature cooler are arranged in series and are part of a cooling line to cool the gaseous suction fluid; the heater 333 is part of a heating line for heating the gaseous suction fluid. The heating line comprising the heater 333 is arranged in parallel with the cooling line comprising the coolers 331 and 332. A first regulating valve V1 is connected at the outlet to the heater 333 to modulate the flow of gaseous fluid through the heater 333 between a closed position and an open position of the control valve V1.

The cooling line also includes a by-pass branch 334 arranged in parallel with the low temperature cooler 332; the bypass branch 334 and the low temperature cooler 332 are selectively connected at the outlet to the high temperature cooler 331. In particular, a second regulating valve V2 is arranged on the by-pass branch 334 to modulate the flow of gaseous fluid through the bypass branch 334 between a closed position and an open position of the regulation valve V2, and a third regulation valve V3 is disposed at the outlet of the low temperature cooler 332 to modulate the flow of gaseous fluid through the low temperature cooler temperature 332 between a closed position and an open position of the regulating valve V3. The control valves V1, V2, V3 can be integrated in a single complex multi-way valve body, and from a constructive point of view they can also form part of the conditioning module 33. More generally, valve means can be arranged along at least one of said heating and cooling lines to modulate the flow of gaseous fluid through them, and in particular they can be associated respectively with the heater 333, the bypass branch 334 and the low temperature cooler 332, possibly with an arrangement different from that shown in the figures.

A control unit 40 is also provided, which can be the engine control unit (ECU), to govern the control valves V1, V2, V3 and the electrical supply to the heater 333 and to the pumps P1, P2 of the circuits. power supply of the high temperature cooler 331 and of the low temperature cooler 332, as indicated by the dashed arrows in Figure 2. The control unit ECU governs the operation of the aforesaid devices on the basis of the conditions of the vehicle. To detect the vehicle running conditions, a series of sensors is operationally associated with the control unit 40. In particular, the control unit 40 receives and processes signals supplied by a possible inlet temperature sensor 351 and by an outlet temperature sensor 352, and indicative of the temperature of the gaseous intake fluid at the inlet (compressor side) and in output (engine side) from the conditioning module 33. The control unit 40 also receives and processes signals supplied by a speed sensor and an accelerator sensor, and respectively indicative of the speed of the vehicle (or of the engine) and of the acceleration required for the vehicle, for example by pressing on an accelerator pedal. The constitution and the positioning methods of the aforesaid sensors are in themselves conventional and not essential for the purposes of the present invention. The signals supplied by the various sensors are represented by dashed arrows in figure 1.

The control unit 40 can be programmed to govern the intake system so as to approximately follow an optimum temperature curve of the gaseous fluid temperature, which can be defined at the design level for the specific engine on the basis of various parameters such as for example:

- Type of engine (petrol, diesel, etc.);

- Engine temperature conditions (warm-up phase, normal operating conditions, severe environmental and load conditions, etc.); - Speed and torque required from the motor;

- Current speed and torque of the motor.

By way of example, Figure 3 represents, as a function of time, a possible CS speed curve of a vehicle that faces different driving conditions, starting from the ignition of the engine at the instant t = 0. A dashed line represents the room temperature, suppository constant. Figure 3 shows a possible temperature curve CT of the gaseous intake fluid (at the engine inlet) in a conventional system equipped with a cooler for the intake fluid, corresponding to the changes in vehicle speed represented by the CS curve. Figure 3 shows a possible optimal temperature curve OT of the gaseous intake fluid at the engine inlet, defined as "optimal" as it optimizes the efficiency and reduction of engine emissions at the specific running conditions represented by the CS curve and at the constant temperature environmental conditions considered in the example. In an aspiration system according to the invention, the control unit 40 can be programmed to govern the various components of the system so as to follow the optimal curve OT as accurately as possible.

After starting the engine and during the warm-up phase (from point 0 to point 4 in figure 3), the control unit 40 can adjust the control valves in order to have the valve V1 open and the valves V2 and V3 closed, so that all the suction fluid passes through the heater 333 (see Figure 4); this can improve engine performance and reduce HC and CO emissions during warm-up.

In a normal running condition (from point 4 to point 5, from point 8 to point 10, and from point 13 onwards), the control unit 40 can adjust the control valves so as to have valves V1 and V3 closed and the regulating valve V2 open, so that all the suction fluid passes through the high temperature cooler 331 (see figure 5), and regulate (by means of the pump P1) the flow of cooling fluid to the cooler 331 to modulate the quantity of heat per unit of time subtracted from the flow of the gaseous suction fluid. This can reduce or eliminate the degradation of engine performance during normal running.

In a condition where acceleration is required from low engine speeds (from point 5 to point 8, and from point 10 to point 13), the control unit 40 can adjust the control valves so as to have the valve V1 closed and the valves V2 and V3 open, so that all the suction fluid passes, as well as through the high temperature cooler 331, also through the low temperature cooler 332 (see figure 6), and adjust (through the pumps P1 and P2) the flow of cooling fluid to the coolers 331 and 332 to modulate the quantity of heat per unit of time subtracted from the flow of the gaseous suction fluid. Under conditions of low engine speed. The additional cooling provided by the low-temperature cooler 332 can improve the dynamic behavior of the engine and reduce turbo-lag, resulting in improved engine driveability.

It is also possible to conceive further operational configurations of the suction system according to the invention, in addition to those described above, such as, for example, configurations with partial opening of one or more of the regulation valves V1, V2 and V3, to achieve the passage of different fractions of the suction fluid respectively through the heater 333 and the coolers 331 and 332 and carry out a subsequent mixing thereof so as to obtain an even finer regulation of the temperature of the suction fluid at the inlet of the engine.

Claims (10)

CLAIMS An intake system for a supercharged internal combustion engine of a motor vehicle, comprising an intake duct (30) having a first end (31) connectable to a supercharging compressor (C), and a second end (32) connectable to a plurality of cylinders (21) of the engine for feeding a gaseous fluid suction to said cylinders, wherein said suction duct includes a cooling line comprising: a high temperature cooler (331) and a low temperature cooler (332) arranged in series along said suction duct, and fed with a cooling fluid provided to cool the gaseous suction fluid, said cooling fluid being fed by a power supply system on board the vehicle; and a by-pass branch (334) arranged in parallel with said low temperature cooler, said bypass branch and said low temperature cooler being selectively connected at the outlet to said high temperature cooler; characterized in that it further comprises a heating line with a heater (333) provided for heating the gaseous suction fluid, said heating line being arranged in parallel with said cooling line, in which said suction system is configured to be modulated between a heating mode in which the suction gaseous fluid is heated through said heater, and a cooling mode in which the suction gaseous fluid is cooled through at least one of said high temperature cooler and low temperature cooler. System according to claim 1, further comprising valve means (V1, V2, V3) arranged along at least one of said heating and cooling lines for modulating the flow of gaseous fluid therethrough. 3. System according to claim 2, wherein said valve means are associated respectively with the heater (333), the bypass branch (334) and the low temperature cooler (332). System according to claim 3, wherein said valve means comprise first valve means (V1) arranged connected at the outlet to the heater (333), second valve means (V2) arranged on the by-pass branch (334), and third means valves (V3) arranged connected at the outlet to the low temperature cooler (334). System according to one of claims 2 to 4, in which said valve means are integrated in a single valve body. System according to one of the preceding claims, wherein said heater, high temperature cooler, low temperature cooler and, optionally, said valve means are integrated in a single conditioning module (33). System according to one of the preceding claims, further comprising a control unit (40) programmed to modulate the intake system between the heating mode and the cooling mode according to the driving conditions of the vehicle, determined by means of a plurality of sensors associated with the control unit (40). 8. System according to claim 7, wherein said control unit is an engine control unit (ECU). System according to claim 7 or 8, wherein said sensors comprise an outlet temperature sensor (352) provided to provide a signal indicative of the temperature of the suction gaseous fluid downstream of the suction system, a speed sensor provided for providing a signal indicative of the speed of the vehicle, and an accelerator sensor provided to provide a signal indicative of an acceleration required for the vehicle. System according to claim 9, wherein said sensors further comprise an inlet temperature sensor (351) provided to provide a signal indicative of the temperature of the gaseous suction fluid at the inlet of the suction duct (30), downstream of the supercharging compressor (C).